Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now


Belar Updates AM Modulation Monitors for HD Radio and MDCL Systems

RF monitoring pioneer adds low-pass filtering to reduce interference with readings and signal quality between standard and digital AM modulation

West Chester, PA, October 23, 2017 — Belar Electronics has unveiled its latest innovations for analog and digital AM modulation, as the RF monitoring pioneer updates its legacy AMMA-2 system for more efficient operation within HD Radio and MDCL systems.

The Belar AMMA-2 is a DSP-based, microprocessor-controlled AM modulation monitor that precisely measures and analyzes positive and negative modulation and carrier level. The AMMA-2 was originally designed for the Voice of America (VOA) to support high-power shortwave transmitters running Modulation-Dependent Carrier Level, or MDCL, algorithms. These MDCL algorithms are today used worldwide to reduce energy use and utility bills associated with high-power transmitters. When combined with an AMMA-2 monitor, broadcasters can now reduce power consumption by 20 percent, lowering monthly costs with no sacrifice to broadcast quality.

“The carrier level in traditional AM broadcasting is constant, and is used as the reference level to determine the modulation of audio being broadcast,” said Mark Grant, CEO, Belar Electronics. “This all goes out the window with MDCL, as the carrier becomes dynamic just as the audio. That makes it impossible to use a standard AM monitor, but by tracking the dynamically moving carrier the AMMA-2 can provide accurate modulation readings.”

Belar has also updated the AMMA-2 with 5 kHz and 8 kHz low-pass filters to provide accurate AM readings in the presence of HD Radio carriers. The filters help broadcasters eliminate any potential interference between analog and digital AM modulation that might affect readings or signal quality, while providing the wider bandwidth needed to support talk (5 kHz) and music (8 kHz). 

“Audio bandwidth becomes the issue when monitoring AM HD Radio signals,” said Grant. “The traditional 10 KHz audio bandwidth passes HD carriers present from 5 kHz to 10 kHz, wreaking havoc with modulation readings,” he said. “Adding the 5 kHz and 8 kHz digital filters in the AMMA-2 removes the HD carriers and preserves the analog readings.”

The AMMA-2 features user-defined parameters and settings for maximum flexibility. Two large up/down menu keys are used to cycle the 16-character alphanumeric display to the desired menu; the up/down parameter keys are then used to select the desired setting. The unit configuration may be saved to the on-board non-volatile memory so the settings are retained in the event of a power loss. For remote connectivity, Belar WizWin software is available for unit control and graphic/logging capability of all AMMA-2 measurements.

About Belar Electronics

Founded in 1964, Belar Electronics Laboratory, Inc. is the world’s leading manufacturer of modulation monitors. Used by radio and TV stations globally to monitor broadcast signals, Belar products are world-renowned for accuracy and reliability. These benefits are also recognized worldwide by manufacturers of transmitters and audio processors, which regularly rely on Belar monitors as test instruments to ensure their products meet specifications. Contact Belar at (610)-687-5550 or visit them on the web at